Refrigerating apparatus



Jan. 31, 1939. H. B. HULL 2,145,354

REFRIGERATING APPARATU S Filed Jan. 51, 1931 5 Sheets-Sheet 1 INVENTOR 7BFW W ATTORNEY Jam. 31, 1939 H. B. HULL 2,145,354

REFRIGERATING APPARATUS Filed Jan. 31, 1931 3 Sheets-Sheet 2 W weINVENTOR M W BY ATTORNEY Jan. 31, 1939. H. B. HULL I 2,145,354,

REFRIGERATING APPARATUS Filed Jan. 51, 1931 3 Sheets-Sheet 3 HHH INVENTOi? Wm M W ATTORNEY M 3% Patented Jan. 31, 1939 UNITED STATES PATENTOFFICEJI REFRJGERATING APPARATUS Harry B. Hull, Dayton, Ohio, assignor,by mesne assignments, to

General Motors Corporation,

This invention relates to refrigerating apparatus and more particularlyto the compression type of such apparatus.

In refrigerating systems of the compression type it is customary toconnect the high pressure or discharge side of the compressor to acondenser and to connect the low pressure or inlet side of thecompressor to an evaporator, the discharge side of the condenser beingin turn connected to the inlet side of the evaporator. Systems of thistype are provided with a body of lubricant, such as lubricating oil, forlubricating moving elements of the compressor. This body of lubricant isstored usually in the compressor crankcase which provides a reservoirtherefor and which is in communication with the inlet of the compressor.In systems of this type where a lubricant, which is miscible withrefrigerant in the system, is used for lubricating the compressor it hasbeen found that where refrigerant from the low pressure side of thesystem is permitted to return to the oil reservoir during off cycles ofthe system in any appreciable amount, a com siderable amount ofrefrigerant is absorbed in the body of oil. Additional refrigerantenters the reservoir, some of which is further absorbed in the oil andsome of which tends to build up pressures in the crankcase. It has alsobeen found that when the pressure of the lubricant thuscharged withrefrigerant, is quickly reduced by operation of the compressor,considerable frothing or foaming takes place in the oil reservoir whichcauses some of the foaming oil to be pumped to other parts of the systemto thus affect the efficiency of the system. In so doing a portion ofthe lubricant is withdrawn from where it is required for lubrication ofthe compressor parts.

One of the objects of this invention is to provide means for graduallyreducing the pressure built up in the crankcase when the compressorstarts its running operation to thus prevent frothing or foaming oflubricant in the crankcase.

Another object is to provide improved means,

for preventing, to any appreciable extent, the absorption of refrigerantin the body of lubricant. Further objects and advantagesof the presentinvention will be apparent from the following description, referencebeing had to the accompanying drawings, wherein a preferred form of thepresent invention is clearly shown.

In the drawings. Fig. 1 is a diagrammatic illustration of arefrigerating system embodying features of my invention, and showing anenlarged view of the compressor partly in cross section and partly inelevation; v I

Fig. 2 is a view similar to Fig. 1 showing a modified form of means forpreventing the pressure in the crankcase from being quickly reduced uponoperation of the compressor; and

Fig. 3 is a view showing other means for preventing the absorption ofrefrigerant in the body of oil in the compressor crankcase.

Referring to the drawings the numeral 20 des- 10 ignates in general arefrigerating system embodying features of my invention. The system 20includes the compressor 22, condenser 23, receiver 24 and evaporator 25.A motor (not shown) is provided for driving the compressor 22 in the 15'I usual manner.

Refrigerant flows through the parts in the order named. That is,refrigerant is compressed in the compressor, discharged through conduit30 into the condenser wherein it is liquefied and from which it passesto the re- 20 ceiver 24. Receiver 24 is connected to the evaporator bymeans of theliquid supply conduit 32. The liquid refrigerant inevaporator 25 vaporizes to produce a cooling effect and the vapors passfrom the evaporator through a vapor conduit 34 25 to the compressor in amanner described hereinafter. In order to provide means for starting andstopping the motor in response to a predetermined high and low pressureconditions within the evaporator I have provided an automatic 30 switch35. The switch 35 is operated by bellows 36 which is responsive topressure within the vapor conduit 34. The motor and compressor arecontrolled in response to predetermined high and low pressure conditionswithin the evaporator. 35 In view of the fact that predetermined highand low pressures vary according to the temperature conditions Withinthe evaporator the motor compressor unit is in reality responsive totemperature conditions in the evaporator. The evapora 40 tor may be ofany desired type, and for instance, may be of the flooded floatcontrolled type similar to that described in the patent to R. G. Osborn,1,556,708 patented Oct. 13, 1925.

Referring more in detail to the drawings the compressor includes acasing 40 which provides a crankcase portion 62 forming a reservoir forlubricating oil. The upper portion of the casing ll] provides a cylinderportion 45 in which reciprocates a piston 38 actuated by pitman 69 which5 in turn is actuated by eccentric 50 carried by a drive shaft 52. Thecompressor also includes a discharge head which is provided with adischarge port 617 to which the conduit 30 is connected. The casing 40is provided with an inlet 5 18 for gaseous refrigerant which is incommunication with the vapor conduit 34 and leads to the crankcaseportion 42. The casing 48 is also provided with an inlet H whichcommunicates with the vapor conduit 34 and leads to the cylinder portion45 of the casing 48. Admission of refrigerant to the inlet 18 iscontrolled by a throttling means 88 about to be described. 7

The throttling means 88 includes a valve proper 82 adapted to open andclose passage 84 in response to pressure within the vapor conduit 34.The valve 82 is enclosed in a casing which carries an expansible bellows81 which is adapted to actuate the valve 82. A chamber 83 formed by thecasing 85 communicates with the vapor conduit .34 and leads to thecompressor inlet H, and leads to the compressor inlet 18 throughpassageway 84 which is controlled by valve 82. As shown in Fig. 1 thepiston 48 is provided with the slotted portion 98 having a passage 92which leads to the central hollow portion 48a-of the piston 48. Duringthe off cycle of the compressor 22 the gaseous refrigerant in conduit 34builds up. a pressure in said conduit and in the chamber 83 which inturn expands the bellows 81 against the action of a spring 88 to actuatevalve 82 to close passage 84. At this time the only gaseous refrigerantwhich is admitted to the crankcase of the compressor passes through ventI88 provided in the valve proper 82. Thus it will be apparent that thebellows 81 will maintain valve 82 closed until bellows 36 actuatesswitch 35 to cause the compressor to reduce the pressure in chamber 83and conduit 34. Thus when the compressor starts operation gaseousrefrigerant will be withdrawn from the chamber v83 into the hollowportion of the piston 48 through the compressor inlet 1I whence it will.be discharged through discharge valve II8 carried in the top of piston48 and later discharged by the compressor into conduit 38 which leads tothe condenser 23. When this takes place some gaseous refrigerant will bewithdrawn from the compressor crankcase through compressor inlet 18 andvent I88. Thus it will be noted that when the compressor starts only asmall amount of gaseous refrigerant will be withdrawn from thecompressor crankcase or in other Words the pressure in said crankcasewill be reduced gradually. -As the pressure within the conduit 34 andthe chamber 83 is gradually reduced the bellows 81 permits the valve 82to gradually open, at which time the pressure in the crankcase has beenmaterially reduced and the remaining gaseous refrigerant therein can bewithdrawn in accordance with the passage provided by valve 82 which isgraduallybeing opened under the influence of the spring 88. By thisarrangement it will be noted that in the .event any oil should becirculated throughout the system. it will be returned to the compressorcrankcase through vapor conduit 34, passage 84 and compressor inlet 18.

Referring now to Fig. 2, there is shown a refrigerating system I28comprising compressor I22, condenser I23 and evaporator I24. Theoperation of this system is similar to the operation of system 28.However, gaseous refrigerant is conducted from evaporator I24 through avapor conduit I34 which leads to the compressor crankcase providing areservoir for a body of lubricating oil. In this modification thecompressor piston I48 is provided with a slotted portion I58 having apassage I52 which leads to a hollow portion I48a of piston I48. The gasfrom the hollow portion I48a is discharged through the valve I68. Theslotted portion I52 communicates with the compressor crankcase through apassage I65. The passage I65 is controlled by a throttling means I18.The throttling means includes a valve I12 actuated by an expansiblebellows I15 and adjustable spring I16. The bellows I15 acts against thespring I16 to close valve I12 when the pressure in the crankcase and inthe bellows increases and the bellows acts under the influence of springI16 to open valve I12 as the pressure in the crankcase and bellowsdecreases. During the oif cycle of the compressor the valve tends toclose passage I65 from the crankcase. Thus, when the compressor starts,the'gas in the bellows I15 will be first withdrawn from the bellows togradually open valve I12. This permits the gas in compressor crankcaseto be gradually reduced to thereby gradually reduce the pressuretherein. This arrangement prevents frothing or foaming of oil in thecompressor crankcase.

In Fig. 3 there is shown another refrigerating system. This system isadapted to be intermittently operated by a motor 288 which drivescompressor 282. The motor 288 is controlled by an automatic switch 285which is responsive to predetermined pressures within the system. Whenthere is a demand for refrigeration by the system the switch 285 placesthe motor in circuit with the power mains to thus drive the compressor.When the compressor is inoperative, the switch 285 connects an electricheating member 2I8 in circuit with the power mains. The heating membermay be any suitable device for heating the lubricant in the system. Asshown in Fig. 3 the heating member 2I8 is disposed below the level ofoil in the compressor crankcase. The purpose of this heating member 2I8is to heat the oil in the compressor crankcase during the off cycles ofthe compressor to thus prevent the refrigerant in the compressorcrankcase from being absorbed in the body of oil. This prevents frothingand foaming of oil when the compressor starts operation.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A closed refrigerating system comprising in combination a compressor,condenser and evaporator, said compressor being provided with a highpressure side communicating with said condenser and a low pressure sidecommunicating with said evaporator, said compressor providing areservoir for lubricant on the low pressure side of said compressorcommunicating with said evaporator, a quantity of lubricant in saidreservoir miscible with said refrigerant, said compressing meansincluding means for withdrawing gaseous refrigerant from said reservoir,com.-

pressing said refrigerant and delivering it to the high pressure side ofsaid compressor, and automatic means for limiting the withdrawal ofrefrigerant from said reservoir.

2. A closed refrgerating system comprising in combination a compressor,condenser and evaporator, said compressor being provided with a highpressure side communicating with said con-' denser and a low pressureside communicatn with said evaporator, said compressor providing areservoir for lubricant on the low pressure side of said compressorcommunicating with said evaporator, a quantity of lubricant in saidreservoir miscible with said refrigerant, said com pressing meansincluding means for withdrawing gaseous refrigerant fromsaid reservoir,conipressing said refrigerant and delivering it to the high pressureside of said compressor, and a valve responsive to pressures on the lowpressure side of said compressor for limiting the withdrawal ofrefrigerant from said reservoir.

3. A closed refrigerating system comprising in combination a compressor,condenser and evaporator, said compressor being provided with a highpressure side and a low pressure side, a conduit connecting saidcondenser to the high pressure side of said compressor, a vapor conduitconnecting said evaporator with the low pressure side of saidcompressor, said compres sor providing a reservoir for lubricant, aquantity of lubricant in said reservoir miscible with said refrigerant,means providing a passage leading from said vapor conduit to saidreservoir, said compressor including means for withdrawing gaseousrefrigerant from said vapor conduit and from said reservoir through saidpassage, and automatic means for restricting said passage.

4. A closed refrigerating system comprising in combination a compressor,condenser and evaporator, said compressor being provided with a highpressure side and a low pressure side, a conduit connecting saidcondenser to the high pressure side of said compressor, a vapor conduitconnecting said evaporator with the low pressure side of saidcompressor, said compressor providing a reservoir for lubricant, a,quantity of lubricant in said reservoir miscible with said refrigerant,means providing a passage leading from said vapor conduit to saidreservoir, said compressor including means for withdrawing gaseousrefrigerant from said vapor conduit and from said reservoir through saidpassage, and a valve responsive to pressures in said vapor conduit forrestricting said passage.

5. A closed refrigerating system comprising in combination a compressor,condenser and evaporator, said compressor being provided with a highpressure side and a low pressure side, a conduit connecting saidcondenser to the high pressure side of said compressor, said compressor,providing a reservoir for lubricant, a quantity of lubricant in saidreservoir miscible with said refrigerant, a vapor conduit connectingsaid evaporator with said reservoir, said compressor including means forwithdrawing gaseous refrigerant from said reservoir, compressing saidrefrigerant and delivering it to the high pressure side of saidcompressor, and automatic means for limiting the withdrawal ofrefrigerant from said reservoir.

6. A closed refrigerating system comprising in combination a compressor,condenser and evaporator, said compressor being provided with a highpressure side and a low pressure side, a conduit connecting saidcondenser to the high pressure side of said compressor, said compressorproviding a reservoir for lubricant, a quantity of lubricant in saidreservoir miscible with said refrigerant, a vapor conduit connectingsaid evaporator with said reservoir, said compressor including means forwithdrawing gaseous refrigerant from said reservoir, compressing saidrefrigerant and delivering it to the high pressure side of saidcompressor, and a valve responsive to pressures on the low pressure sideof said compressor for limiting the withdrawal of refrigerant from saidreservoir.

7. A closed refrigerating system comprising in combination, acompressor, a condenser and an evaporator, said compressor beingprovided with a high pressure side communicating with said condenser anda low pressure side communicating with said evaporator, said compressorproviding a reservoir for lubricant on said low pressure side of saidsystem, a quantity of lubricant in said reservoir miscible withrefrigerant in the system, means within the compressor for withdrawinggaseous refrigerant from said reservoir and said evaporator and forcompressing same and delivering said compressed refrigerant to the highpressure side of the system, and pressure responsive means interposed inthe path of flow of gaseous refrigerant from said evaporator to saidfirst named means for restricting the flow of gaseous refrigerant fromsaid reservoir to said first named means during one part only of theoperation of said first named means.

8. Refrigerating apparatus comprising a closed refrigerant circuitincluding a. compressor having a compressing chamber and a lubricantreservoir substantially separated from the closed circuit, a condenserand a cooling unit, a chamber in said closed circuit for collectinglubricant from the refrigerant, a conduit connecting said chamber andthe lubricant reservoir, and a valve in said conduit tending to restrictflow through said conduit during periods when-the lubricant in saidreservoir tends to foam.

9. Refrigerating apparatus comprising a closed refrigerant circuitincluding a compressor having a compressing chamber and a lubricantreservoir substantially separated from the closed circuit, a condenserand a cooling unit, a chamber in said closed circuit for collectinglubricant from the refrigerant, .a conduit connecting said chamber andthe lubricant reservoir, and a valve in said conduit tending to restrictflow through said conduit during periods when the lubricant in saidreservoir tends to foam and a bleeder vent in said valve.

10. Refrigerating apparatus comprising a closed refrigerant circuitincluding a compressor having a compressing chamber and a lubricantreservoir substantially separated from the closed circuit, a condenserand a cooling unit, a chamber in said closed circuit for collectinglubricant from the refrigerant, a conduit connecting said chamber andthe lubricant reservoir, and means in said conduit tending to restrictthe fiow of refrigerant through said conduit during the starting periodsof said compressor.

11. Refrigerating apparatus comprising a closed refrigerant circuitincluding a compressor having a compressing chamber and a lubricantreservoir substantially separated from the closed circuit, a condenserand a cooling unit, a chamber in said closed circuit for'collectinglubricant from the refrigerant, and means providing a restrictiveorifice connecting said chamber and the lubricant reservoir and tendingto restrict the flow of refrigerant from said reservoir to said chamberduring the starting period of said com- DIGSSOI.

HARRY B. HULL.

